Device for influencing a lighting installation as a function of ambient light

ABSTRACT

The invention relates to a device for influencing a lighting installation, and more particularly, includes a lighting installation of a motor vehicle, depending on ambient light. The device comprises a switching device to turn the lighting installation on and off. At least one optical sensor is provided to detect the wavelength of the ambient light. An evaluation device sends a control signal to the switching device when the wavelengths of the ambient light detected by the sensor are essentially those contained in the daylight. Since the filter and the sensor are jointly formed by at least one light emitting diode which operates as a light-sensitive element, the passing lights can be automatically turned on in a simple and favorable manner.

BACKGROUND

1. Field of the Invention

The invention relates to a device for influencing a lightinginstallation.

2. State of the Art

The present type of lighting installation frequently appears in thestate of the art and, in a vehicle, serves to turn on and turn off,e.g., the exterior lighting of a vehicle consisting of headlights andtail lights. Because of the risks that arise when operating a vehicleunder conditions of poor visibility or in twilight without turning onthe lights, it is frequently desirable for the low-beam headlights of avehicle to be turned on automatically and without the assistance by thevehicle operator.

It already has been proposed for this purpose, in DE 37 37 396 A1 and DE196 08 184 C2, to employ a sensor device that detects changes in theambient light and that turns on or turns off a lighting installation asa function of such changes. In this connection, the knowledge isemployed that daylight contains wavelengths of light that may bedetected unequivocally and which are not present in darkness or in theambient light, or even in the presence of street lighting. Consequently,an optical filtering device is used in both cases, which, however,always is required in addition to the sensor and which filters thewavelengths of daylight. This occurs either by means of a precedingfiltering glass, which, according to DE 37 37 395 A1 is a specialtyglass of the Schott company, Mainz, or, according to DE 196 08 184 C2, aUV filter permanently fixed to a brightness sensor or, simply slippedonto the latter or to the holder of same. Alternatively, a correspondingfiltering layer may be applied directly to a brightness filter by meansof vacuum evaporation, spray-painting or conventional painting.Consequently, each case requires an additional step and an additionalfiltering device.

As is well known, many vehicle operators have decreased perceptiveability in darkness, which is further decreased by dampness or moistureon the windshield. In this respect, it already has been proposed, inDE-A 41 34 432 and in DE 196 03 663 C1, to control a precipitationsensor as a function of ambient light. At the same time, either a straylight detection device was assigned to an optical precipitation sensoror the precipitation sensor itself was used as a brightness sensor byfiltering the signals to detect and evaluate the share of ambientbrightness.

SUMMARY

From such a point of departure, the underlying purpose of the presentinvention is to create a device which, in a simple and favorable manner,automatically provides for the low-beam headlights to be turned on.

Since the boundary between day and night generally lies in the greenregion of the visible light spectrum, the wavelengths present indaylight may filtered simply by connecting, e.g., a green LED, as alight-sensitive detector. The signals of the green LED then aresimultaneously the control signals for the switchgear, where, for acorresponding adaptation of the loud resistor of the LED, preferably, ahigh-resistance resistor, a reaction occurs which is limited to acertain wavelength range of light, preferably green light.

The fact that wavelengths in the green light region are only presentduring the day may also be used to advantage in connection with a watersensor. A water sensor of this type is known, e.g., from DE-GM 93 09837.5. The optoelectronic measuring arrangement proposed therein workswith at least two measuring areas, the signals of which are guided backto zero at the receiving end with a time constant which is shorter thanchanges which occur as a result of moisture. Consequently, windshieldwiper control can be actuated automatically on the basis of detecteddynamic changes, such that actuation of the windshield wipers alwaystakes place at the time that the motor vehicle operator would alsomanually actuate the windshield wipers.

It is preferable for the present device to operate with LEDs in the redregion of visible light, or in an invisible infrared region, and thus,clearly separate from the green light region which is decisive inturning on the low-beam headlights. In this way, both sensors may beintegrated in one housing without mutual hindrance. However, there is asimultaneous possibility of employing a day/night recognition sensoralso in order to influence control of the windshield wipers. In thisrespect, a precipitation sensor may be influenced as a function of lightconditions; thus, e.g. a windshield wiper, in the presence of the twoconditions “night” and “moisture” on the windshield, would wipe at ahigher speed than it would during the day.

BRIEF DESCRIPTION OF THE DRAWING

In the following, the invention is explained in greater detail with theaid of an embodiment example and the accompanying drawing in which:

FIG. 1 shows a diagrammatic representation of the front end of a vehiclewith an accompanying sensor device according to the invention; and

FIG. 2 shows a front view of the sensor device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be explained in an example with reference to theenclosed drawing. However, the embodiments are merely a matter ofexamples and do not limit the concept of the invention to a specificphysical arrangement.

The device serves to influence a lighting installation 11, particularlythat of a motor vehicle 12, as represented in FIG. 1. This is a matterof the normal parking lights and low-beam headlights of a vehicle. Adriver usually operates the device manually by means of a switchgear 13,at least in order to turn on and off the lighting installation 11,provided that a change occurs in the lighting conditions of the ambientlight.

The device 10 includes at least one sensor 17 for detecting wavelengthsof ambient light. An ancillary evaluating device 14 is provided whichproduces a control signal S, if the wavelengths of ambient lightdetected by the sensor 17 are wavelengths which are containedpredominantly in daylight and therefore preferably feature a wavelengthwhich is shorter than that of the green light. If a control signal S isobtained, then the control signal S serves to actuate the switchgear 13for turning on the lighting installation 11.

Sensor 17 and the evaluation device 14 feature a filter F in the form ofan LED, which filters, in essence, the wavelengths contained indaylight. Consequently, only filtered wavelengths reach the evaluationdevice 14; thus, preferably, wavelengths less than or equal to thewavelengths continued in green light. However, it is self-evident thatfor the present invention, the boundary may be pushed still further inthe direction of the region of the red light or in the oppositedirection. At this time, e.g., blue LEDs also are being developed whichare suitable for this application.

A green LED 15 jointly forms the filter F and, at the same time, alsothe sensor 17. On the basis of its construction, a green LED, inasmuchas this is interconnected as a light-sensitive element, automaticallyreacts only to the wavelengths of light contained in daylight andconsequently has a filter effect. In this respect, the LED 15 itself maythen produce the control signal S for the switchgear 13.

At the same time, one uses the knowledge that an LED emits light only ina limited spectral range based on the material used in each case for thecrystal of the LED. For a green LED, the crystal consists, e.g., of agallium arsenide-doped semiconductor material, which essentiallyradiates only at a certain wavelength. Consequently, if the LED isinterconnected as a receiving element, these narrowly delimited spectralproperties are utilized such that the LED receives only in an extremelynarrow wavelength range. Consequently, the use of an additional filter,which would be mounted separately or produced separately, would beunnecessary. Consequently, the crystal 15 a of an LED 15 interconnectedas a receiver, is itself already the filter F. Consequently, not only isthe manufacturing process more favorable, in addition, one may go backto LEDs which are more favorable in comparison to photodiodes, such thatmanufacturing expense may be reduced.

Thus, in order to use the signals established not only for turning onthe low-beam headlights and, in addition, in order to achieve a compactconstruction, a sensor 17 may be integrated with a green LED 15 in ahousing 18 that includes a water sensor 19, particularly, if the watersensor 19 operates optoelectronically, as explained, e.g., in DE GM 9309 837.5.

Because the water sensor 19 generally detects a coating or moisture on asurface, such as the windshield 16, in the red or infrared wavelengthrange of light, both sensors, i.e., sensor 17 having a green LED 15 andwater sensor 19 having a red LED, may be integrated in a single housing18 and operated next to each other provided that it is assured that bothoperate within different optical wavelength ranges, which do notoverlap, or only slightly overlap. In the embodiment, a water sensoroperates in the infrared range, a display element which emits red lightis present and the LED 15 reacts to green light. Based on the narrowlydelimited spectral properties, the use of LEDs as receiving elementsleads to a case in which different optical measuring systems may beoperated together in a single housing, with the receiving element itselffiltering out the wavelength range relevant in each case. This meansthat measuring areas need not be provided which are dimensioned andseparated from each other or incoming signals need not be subsequentlyfiltered. If necessary, the LEDs may even be arranged directly next toeach other.

This arrangement then has the advantage that a night light recognitionmay simultaneously transmit signals, if necessary, even within thesensor housing, which influence the control device for the windshieldwiper 21. When the sensor 17 essentially no longer locates wavelengthsof daylight, the control signal S may transmit a signal W simultaneouslyto the control device 20 for the windshield wiper 21, which is actuatedas a function of moisture detected by the water sensor 19. This usuallyoccurs when “night” and “moisture” are detected simultaneously. If bothconditions are present, then the control device 20 may drive windshieldwiper 21, e.g., at a higher speed than would take place during the dayoperation.

It is self-evident that this description may be subject to the mostdiverse modifications, changes and adaptations, which are within therange of equivalence to the subordinate claims.

What is claimed is:
 1. A device for influencing a lighting installationas a function of ambient light, comprising a switchgear at least forturning on and turning off the lighting installation; at least oneoptical sensor for detecting a wavelength of ambient light; anevaluation device for producing a control signal if the wavelengths ofambient light detected by the sensor are wavelengths which areessentially contained in daylight, with the control signal actuating theswitchgear for switching the lighting installation; a filter thatessentially filters the wavelengths of light that are contained indaylight, characterized in that filter and the sensor are formed jointlyby means of at least one LED which is interconnected as alight-sensitive element.
 2. The device of claim 1, characterized in thata crystal material of at least one LED is transmissive, as the filter,to wavelengths of light in the region in which the LED emits light. 3.The device of claim 1, characterized in that the LED is one of a greenLED and a blue LED.
 4. The device of claim 1, characterized in that thesensor is integrated in a housing which includes a water sensor whichoptically detects one of moisture and a covering of a surface, with thesensor and the water sensor operating on different optical wavelengthregions, which do not substantially interfere with each other.
 5. Thedevice of claim 4, characterized in that if the sensor essentiallydetects no wavelength of daylight, the control signal simultaneouslytransmits a signal to a control device for a windshield wiper, which isactuated as a function of the moisture detected by the water sensor.